Roadway surface marking, and marked road



Sept. 3, 1968 I. eaezmnmu ROADIIAY SURFACE MARKING. AND MARKED ROADFiled on. 25. 1 966 INVENT OR. is {a} A um EMJ. ow

United States Patent 5 Claims. (Cl. 94-1.s

This application is a continuation-in-part of application Ser. No.262,658 filed Mar. 4, 1963.

This invention relates to the art of marking surfaces subject tomark-obliterating traffic, and more particularly to the marking oftraflic lines and other directional data upon the pavement on streetsand highways, by applying on and securing road marking tape material tosaid pavement.

Roadmarks consisting of tape or strip materiale are well known in theart, as being very advantageous in respect with conventional traflicaids, such as road-center lines, which are customarily painted upon thestreet or highway pavements with ordinary paints. The road-marking stripmaterial is capable of resisting to the most severe traffic and itsapplication to street and highway conventional surfaces requires littleor no interruption to traflic. Such application can advantageously bemade by making use of mechanical aids, such as the apparatus describedand shown in my prior Patent No. 3,007,838.

The very scope of road marking is obviously to provide on the street orhighway pavements signs and traflic data which have high daytime andnighttime visibility to motorists. Road-marking strip or tape materialsas above considered can be compounded to provide traflic indicative highvisibility surface portions on the marked road. The concept of highvisibility is to be intended in its broadest meaning and cannot bedefinedas far as the invention is concernedin terms of brilliance andexpressed by numerical values. Such traflic aids cannot be compared witha source of radiant energy, and are capable of reflecting ambient lightonly. Therefore, a high visibility surface portion, within the scope ofthis invention, Will hereinafter be termed high light reflectivitysurface portion.

The character of high reflectivity is however at its turn difficult todefine as, according to scope of the invention, an efliciently markedroad is a road having a roadway surface and traffic regulating signslocated thereon, said signs being such to be distinctly and clearly seenand neatly evidenced at distance by motorists, under the most differentconditions of illumination. Many variables are involved in thevisibility of road markings and of traflic conditions in general. Thetraflic occurs under bright sun light and in rainy Weather and dimambient light, and at nighttime the roadway surface can be illuminatedby powerful vehicle headlamps or by rather weak streetlamps, andtherefore both intensity and direction of incident light are subject tothe most wide variations.

As a matter of fact, one means for defining the visibility of a roadmarking or, more properly, the visibility of a traffic aid of the typeconsidered on a roadway surface, is to compare the apparent brillianceof the road marking material considered, in several daytime andnighttime limit conditions, with the apparent brilliance of anidentically shaped and positioned surface portion of a material of wellknown and measured reflectivity of visible light. A smooth surface of alayer of pure baryta (BaO) white may be assumed as a suitable basis ofcomparison. A road marking can be considered to have high reflectivitywhen, as photometrically compared as above with a simi- 3,399,607Patented Sept. 3, 1968 larly shaped, located and illuminated sign ofpure baryta, it is proved to have at least sixty percent apparentbrilliance of said basis of comparison.

Therefore, the expression high reflectivity, anywhere hereinafterindicated as this description proceeds and in the appended claims, isintended to refer to a surface portion which, when photometricallycompared with a surface portion of pure baryta white, it averages atleast 60 percent apparent brilliance of its basis of comparison.

It has however been found that a marking tape material having the aboveor desirably better high reflectivity property does not possess the mostdesirable non-skid properties for ensuring the most desirable safemovement and control of fastly running vehicles, in particular whensubject to intense positive or negative accelerations and/ or tocentrifugal force. It is assumed that a roadway surface portion isnon-skid when its adherence coefficient, with respect to current tiredvehicles, averages the value of 40, in terms of angle to the horizontalat which a force corresponding to the weight applied to loaded tiredwheel is directed to cause skidding of said wheel along the surfaceunder test. The concepts of adherence offered by roadway surfaces andthe modes for measuring same are well known in the art of roadwayengineering and no further discussion is necessary thereabout.

It is therefore an object of this invention to provide a marked roadwhich comprises a conventional surface for vehicles and a traflic aidconsisting of tape material having both high light reflectivity andnon-skid properties.

According to the invention, there is provided, on a conventional roadwaysurface, a compound tape material consisting of a first base striphaving relatively non-skid properties and high light reflectivity, saidbase strip being adhesively adherent to said roadway surface, and stripcomponents formed of a material having lesser light reflectivity thansaid first strip and non-skid properties, said strip components beingaligned in longitudinal direction of the first strip and are adherentthereto equally spaced from the lateral edges of the first strip,whereby, on the surface of the road, a composite marking strip is formedhaving exposed portions formed by the first strip and having high lightreflectivity and exposed center portions having non-skid properties.

By thus providing the strip with distinct portions of high lightreflectivity and respectively of non-skid character, the well knowndisadvantages and limitations of conventional marked road areeliminated, inasmuch as the marked road according to the presentinvention will, in its marked surface portion, possess the mostdesirable high light reflectivity as well as higher non-skid propertiesthan could be obtained up to now in combination with the desired degreeof light reflectivity.

According to one embodiment of this invention, a strip formed of amaterial having non-skid properties and having a lesser width than saidfirst high light reflective base strip is extended in longitudinaldirection and adhered to said base strip equally spaced from the lateraledges thereof so as to provide a composite surface formed of two spacededge portions of said first strip having high light reflectivity and ofa center portion having non-skid properties and a lesser lightreflectivity interposed between said two spaced edge portions of saidfirst strip.

According to a modified embodiment of this invention, strip elementsmade of said material having non-skid properties are adhered to saidbase strip equally spaced from the lateral edges thereof and evenlyspaced from each other in longitudinal direction.

It has been surprisingly found that the actual visibility of the traflicaid, in terms of clear and distinct detection thereof by motorists, isnot appreciably reduced by the provision of non-skid portions ofsubstantially lesser high light reflectivity on the whole markingsurface, provided that the portion or portions having non-skidproperties do not cover more than fifty percent of the area of saidmarking surface and that edge portions having high light reflectivitysurfaces will uninterruptedly extend lengthwise the marking. As a matterof fact, the actual visibility, when considered as above, is apparentlydue to sharp reflectivity and color contrast with adjacent conventionalroadway rather than amount of reflected radiations.

It has been further found that a surprising improvement of safe trafficand control of vehicles is attained by providing a marked road with atraflic aid having a compound surface as above, provided that at leasttwenty percent about of said surface of the marked area will possessnon-skid properties.

These and other objects and advantages of the invention are in partobvious and in part will be made apparent as this description proceeds,and the features which are believed to be new and characteristic of theinvention are in particular set forth in the appended claims. Theinvention itself, however, will be best understood from the followingdetailed description of preferred forms of em bodiment thereof, whentaken in conjunction with the accompanying drawings, forming anessential component of this disclosure, and wherein:

FIGURE 1 is a diagrammatical perspective fragmentary view of a markedroad according to first embodiment of the invention;

FIGURE 2 perspectively and diagrammatically illustrates how the compoundstrip material components can be preformed and assembled;

FIGURE 3 similarly illustrates a marked road according to a modifiedembodiment of the invention;

FIGURE 4 is a perspective exploded view of the compound material of FIG.3; and

FIGURE 5 illustrates a further embodiment of the invention.

Referring more particularly to the drawings, FIG. 1 shows a specificmethod of forming and applying a road marking compound material to aroad surface S to actuate a centre or a track-dividing line, forexample, or other sign having a given transverse dimension W forvisibility.

According to current knowledge, such transverse dimension W is however agreat deal larger than the size which might theoretically give therequired visibility, i.e. the ability of reflecting the desired amountof light, provided that the sign has a clean, smooth and undamaged upperface. Adverse weather and lighting conditions are obviously to be takeninto account in dimensioning such trafiic regulation signs.

From another standpoint of view, however, there is a tendency to limitsuch transverse dimension within certain limits, six inches for example,because the currently elasto-plastic marking material have a more orless skidding upper face, on which vehicles tires may easily skid withconsequent prejudice of safety. It is known that a road marking materialis as much visible and lightreflecting as it is smooth and skidding.Smoothness of the light-reflecting upper face of such materials is alsocritical for preventing said face to become readily dirty and dark, andtherefore poorly visible.

By dividing the whole transverse dimension W of the sign means totalsurface, which will be hereby and in the appended claims defined asmarked area, in parts relatively coarse and non-skid and of relativelylow visibility, and in parts of high reflectivity, said latter partsbeing adjacent to the marked area side edges, provided that the area oflatter is at leasty fifty percent of the whole marked area, it has beenfound that the actual visibility of the sign will not substantially beprejudiced. It has been found that, at eyesight, clear visibility ofsuch signs is essentially dependent on clear visibility of the side edgeportions thereof.

Now, it might be assumed that the centre portion W wide of the markedarea is not essential for improving "i 5 1 the visibility of the wholesign and, therefore, such centre portion W wide may beadvantageouslymade such to possess improved non-skidding properties,essentially as an uncovered conventional road surface is. In addition,it might be assumed that the whole width W of the marking material maybe increased with respect to the width of conventional elasto-plasticmarking strips, as a consequence of the provision of the non-skid part Wwide thereinto, the limit of such increment being given by the width ofthe portions designed for high light-reflection, individuallyconsidered.

According to what above, W is from 33 to 50 percent of W and W is offour inches or above, according to the size and importance and averagetraflic speed of the marked highway, according to current art of roadmarking, a W width over six inches being however preferred.

The compound strip of FIG. 1 consists of a first base strip 10 of highreflectivity material, lengthwise recessed at 12, and of a strip 14 ofmaterial having non-skid properties, seated into and firmly secured inthe recessed portion of the base strip.

According to FIG. 3, the base strip has recessed portions 22 (FIG. 4)evenly spaced from the lateral edges thereof and wherein flat pieces 24of non-skid properties possessing material are seated and secured insaid recesses. Length L of individual pieces 24 may be comprised between10 to 50 millimeters and the interval I therebetween may be comprisedbetween 20 and 100 millimeters.

According to FIG. 5 two parallel longitudinal rows of pieces 34 spacedfrom each other and from the lateral edges of base strip are providedfor imparting nonskid properties to the traflic aid, the number of suchrow and the dimensions of the pieces being matter of choice, providedthat a firm connection of said pieces to said base strip is ensured toresist to traffic and to wear and shearing forces induced thereby.

Some examples of formulations and of compositions of components will bedescribed hereinbelow for best understanding of the invention and of thediffering modes for carrying out same.

Example 1 This example illustrates formulations and combinationsparticularly adapted for producing a compound marking material the typeshown in FIG. 1, which includes two components, namely a first highreflectivity component and a second non-skid component/The respectivecompositions contents, expressed in terms of weight, will be indicatedunder HR (for High Reflectivity) and NS (for Non-Skid), respectively:

Content N-S Butadiene-acrylonitrile copolymer, having 38% acrylonitrile(acrylonitrilic rubber Chemigum No. 3, by Goodyear) 20 20 Maleicmodified polyvlnyl-chloroacetate copoly'mer (Vinilite VMCH" by UnionCarbide) 40 40 Mieromized calcium carbonate... 25 Talcum 0000 25Zirconium oxide (average diameter .5 mils) Example 2 A marking materialfor providing a marked road of the type shown in FIGS. 3 and 5 have beenproduced from the following compositions, by weight:

High reflectivity base trip component:

Butadiene-acrylonitrile copolymer, having 38% acrylonitrile 12 Maleicmodified polyvinyl chloroacetate copolymer 37 Titanium dioxide (rutile)20 Kaolin 0000 25 Micromized calcium carbonate 28 Five parts of asuitable plastifier, such as a coumaronic resin, can be added. Thecompound is processed and laminated in strip form at 150 C.

Non-skid components:

Polychloroprene (such as Neoprene WHV The compound has been processedand laminated at 90 C., and the desired pieces have been cut therefrom.Such pieces have been applied and secured to the base strip component,at 90 C., by making use of a glue consisting of Glue:

85% styrene polymer-% butadiene polymer,

such as Marben 8000 A by Marbon Chemical 5 Clear natural rubber 5 Benzol50 Dichloroethane 40 While the invention has been described and shown infew forms of embodiment thereof, it is obvious that the invention itselfis not limited to the very details shown, and that further modificationsand variations might be made thereto, according to the art.

What is claimed is:

1. A marked road, comprising in combination, a roadway surface forvehicles; a first strip of road marking tape having relatively lownon-skid properties and high light reflectivity joined to the upper faceof said roadway sur face; and another strip formed of a material havingnonskid properties and a lesser light reflectivity than said first stripof road marking tape and having a lesser width than first stripextending in longitudinal direction and adhered to said first stripequally spaced from the lateral edges thereof so as to provide togetherwith said first strip a composite surface formed of two spaced edgeportions of said first strip of road marking tape having relatively lownon-skid properties and high light reflectivity and of said other stripforming a center portion having non-skid properties and a lesser lightreflectivity interposed between said two spaced edge portions of saidfirst strip.

2. A marked road according to claim 1, wherein the width of said anotherstrip is from one third to one half of the width of said first strip.

3. A marked road, comprising in combination, a roadway surface forvehicles; a first strip of road marking tape having relatively lownon-skid properties and high light reflectivity adhesively joined to theupper face of said roadway surface; and strip components of a materialhaving non-skid properties and a lesser light reflectivity than saidfirst strip of road marking tape, said strip components being evenlyspaced from each other and from the lateral edges of said first stripand adhered to said strip so as to provide together with said firststrip a composite surface, longitudinally and laterally spaced portionsof said first strip of road marking tape having high reflectivity andother portions spaced from said edges and having non-skid properties.

4. A marked road according to claim 3, wherein sum of the area of saidportions having non-skid properties consists from twenty percent tofifty percent of the area defined between said lateral edges of firststrip.

5. A marked road according to claim 3, wherein said portions havingnon-skid properties are arranged in a row of spaced elements equallyspaced from the lateral edges of said first strip.

References Cited UNITED STATES PATENTS 2,225,496 12/1940 Gethin 94-l.52,898,825 8/1959 Walker 94-1.5 3,011,412 12/1961 Harrington 94--1.53,049,980 8/1962 Gill 941.5

NILE C. BYERS, Primary Examiner.

1. A MARKED ROAD, COMPRISING IN COMBINATION, A ROADWAY SURFACE FORVEHICLES; A FIRST STRIP OF ROAD MARKING TAPE HAVING RELATIVELY LOWNON-SKID PROPERTIES AND HIGH LIGHT REFLECTIVELY JOINED TO THE UPPER FACEOF SAID ROADWAY SURFACE; AND ANOTHER STRIP FORMED OF A MATERIAL HAVINGNONSKID PROPERTIES AND A LESSER LIGHT REFLECTIVITY THAN SAID FIRST STRIPOF ROAD MARKING TAPE AND HAVING A LESSER WIDTH THAN FIRST STRIPEXTENDING IN LONGITUDINAL DIRECTION AND ADHERED TO SAID FIRST STRIPEQUALLY SPACED FROM THE LATERAL EDGES THEREOF SO AS TO PROVIDE TOGETHERWITH SAID FIRST STRIP A COMPOSITE SURFACE FORMED OF TWO SPACED EDGEPORTIONS OF SAID FIRST STRIP OF ROAD MARKING TAPE HAVING RELATIVELY LOWNON-SKID PROPERTIES AND HIGH LIGHT REFLECTIVITY AND OF SAID OTHER STRIPFORMING A CENTER POSITION HAVING NON-SKID PROPERTIES AND A LESSER LIGHTREFLECTIVITY INTERPOSED BETWEEN SAID TWO SPACED EDGE PORTIONS OF SAIDFIRST STRIP.